Morality is the cornerstone of all politics. Socrates, in the Gorgias, declared that the purpose of politics is the instruction of virtue to citizens. From 1945, Britain faced a plethora of political problems, some perennial, some new: decolonisation, immigration, class disparity, war and the welfare state. They all required ethical debate and underpinning them is a vital question: how far can abstract moral arguments be deformed, reformed and compromised when entered into the impassioned, fractured and ambitious world of politics?

None of these issues is discussed in Andrew Holden's new book. Instead of a history of morality, we get a history of moralising. The usual high horses are trotted out: homosexuality, sex education, contraception and pornography.

Despite endorsing the position of Edward Boyle, Macmillan's minister of education, that morality is not simply sexual morality, much of the book is concerned with this uninteresting area of ethical debate. Reforms in these areas were, and continue to be, important but they are an eradication of prejudice rather than the resolution of serious moral conflict.

The banality of subject matter is reflected in the banality of Holden's philosophising. He finds it surprising that 'Leo Abse, non-practising Jewish sponsor of homosexual and divorce law reform, remained fervently opposed to abortion on the grounds that it destroyed life'. Discrimination against homosexuals is so indefensible that there is no moral debate to be had (or at least none that is not stymied with 'But God says it's wrong'). It is difficult to see, however, why support of homosexual law reform should necessarily entail support of abortion, which clearly merits serious discussion, whatever one's final opinion.

Holden operates out of a 'liberal' position, which is more connected with political posturing than ethical engagement. There is also the nasty implication that Abse's almost impeccable liberal credentials are sullied by a moment of ill-repressed Judaic conscience.

The book is infused with similar slurs. Right-wing thinkers invariably speak 'jeremiads' and oppose reforming measures with 'howls of derision' (occasionally they 'hoot').

The distinction between morality and legislation that is based on it remains confused throughout. Apparently, the fundamental principle to emerge from the Warnock inquiry into fertilisation and embryology was that 'a regulatory body, independent from government, should be set up to monitor developments and regulate treatments and research'. This is recommendation (and a rather nebulous one at that) for the enforcement of moral principle, not the principle itself.

This book could have analysed the language of moralising and shown how it is deployed and modulated across the ideological spectrum. Generally, it chooses to quote rather than analyse but on the few occasions he examines rhetoric, Holden proves to have a tin ear. Tony Blair's declaration that he was 'appalled' to hear of the pregnancies of two teenage girls in Rotherham is said to echo the Daily Mail's claim that teenage sex was 'a way of life' in Rotherham.

There is a vast gap between expressing concern at the problems and obstacles that a child may cause to education and enjoyment of one's youth and the Mail 's ridiculous hysteria that teenagers were making all their decisions, great and small, through the haze of post-coital fag smoke.

Though most of the book is gummed up by tediously retracing the progress of specific pieces of legislation through commissions, committees and parliament, a dismal picture of the place of ethical debate in public life emerges. The Labour government of the late Sixties, urged on by Roy Jenkins at the Home Office, sanctioned most of the major liberal social reforms we enjoy today: decriminalisation of homosexuality, easier abortions and abolition of theatre censorship. But this was done in the teeth of opposition, or apathy, by much of the rest of the administration. Reforms were generally initiated by independent-minded backbenchers such as Leo Abse, David Steel and Sydney Silverman, who fought for the abolition of capital punishment.

Throughout the last 60 years, governments have rarely got involved in discussing difficult moral issues, preferring to devolve serious thinking to royal commissions and committees of inquiry whose memberships are carefully formulated to produce the most palatable fudge possible.

The justification of the peculiarly British bumbling of social reform would make a fascinating history. Unfortunately, this book, whose judgments veer from the dazzlingly obvious to the infuriatingly noncommittal, does not provide it.